Managing Power Supplies

Amy had a customer question on power supply failure:

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I have had my customers ask me about this feature a couple of times now. They are concerned that the power supplies are not ‘rotated’ while in dynamic power savings mode. For example, an enclosure with an average load running for 4 years may never use PSU 3 and 6, and will not know they are faulty until a power supply fails. The idea in their minds is that power supplies should be rotated, much like the tyres on a car. Are you able to comment whether this idea reflects reality? Are the power supplies rotated over time to ensure even ‘wear’?

If not, do we recommend disabling dynamic power savings regularly to ‘test’ the power supplies?

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Monty replied:

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The Onboard Administrator (OA) performs a diagnostic test every 24 hours on each power supply that is placed in standby by Dynamic Power Savings.

Basically, the OA turns on one of those power supplies, tests that it shares the enclosure load properly, then places it back in standby if it passes the test.

If this test fails, the OA will mark the power supply as failed.

The power supply design team indicates that placing power supplies in standby or active, or switching them on and off does not affect their reliability.

Yes, I believe the easiest way for customers to manually check the power supplies in standby would be to disable Dynamic Power Savings, examine the power supply output, then enable DPS again. But if the OA is performing this task on a daily basis – it seems the only reason to do this manually is during the initial qualification phase to gain confidence in the fault tolerance of the system.

Remember that each customer workload is likely unique, so the actual benefit of a feature like Dynamic Power Savings should be evaluated during initial qualification to determine whether it should be enabled or disabled to get the highest efficiency for the entire enclosure. We have also improved the c7000 power supply efficiency with two newer 2400W power supplies. The more efficient the power supplies, the less the benefit of Dynamic Power Savings. The original c7000 power supply efficiency peaked around 85%. The latest Platinum 2400W power supplies peak at 94% and have a higher efficiency over a wider output range.